How to add Transparency according to the depth and Color according to the isovalues in isosurface function?

I have a 3D matrix which I attached here (Iso.mat). Now If I simply use the following command, then I am getting the attached figure(Iso.jpg).

isosurface(diff); alpha(0.4); axis off;

Is it at all possible to add Transparency according to the depth and Color according to the isovalues in isosurface function? I want the dark inside and light outside. Here I have found one image on the web which expresses my problem.

Voxler 4